NIOSH tools for hearing loss prevention programs

A.S. Azman, R.F. Randolph and R.L. Hudak Research audiologist, research psychologist and occupational health nurse, respectively, National Institute for Occupational Safety and Health, Pittsburgh, Pennsylvania

Abstract The mining workforce experiences high rates of hazardous noise exposure and hearing loss. However, previous studies have identified specific behavioral and attitudinal barriers that keep miners from effec- tively acting to prevent their own hearing loss. The National Institute of Occupational Safety and Health (NIOSH) has developed several new hearing loss prevention tools and interventions that specifically target these barriers to prevention. The NIOSH Hearing Loss Simulator addresses motivation to take action and knowledge about the consequences of noise exposure. The QuickFit earplug test device and QuickFitWeb online hearing protection tester address barriers to effective earplug and earmuff use by verifying at least 15 decibels of protection. The NIOSH Roll-Pull-Hold technique helps miners obtain better protection through an easy-to-remember set of steps that improves attenuation by nine decibels. The “Inquiring Ears Want to Know” fact sheet helps miners to understand audiograms and to use them to maintain their hearing health. Each of these interventions can be used within the context of a com- prehensive hearing loss prevention program.

Introduction tion and motivation to play a critical role in preserving their The mining workforce experiences high levels of noise own hearing. exposure and in turn suffers from high rates of noise-induced Previous studies have identified attitudinal and behavioral hearing loss (NIHL). The mining sector has the highest preva- barriers that prevent miners from acting to effectively protect lence of hazardous workplace noise exposures (76%) among their own hearing. Virtually all of these studies examine the all industrial sectors (Tak et al., 2009). Although most miners use or non-use of hearing protection, although noise controls use hearing protection and diligent effort is put forth both by are the preferred method of hearing loss prevention. A positive manufacturers and researchers to quiet mining machinery, association has been identified between attitudes regarding miners continue to exhibit a high prevalence (24%) of hear- hearing protection and behavioral intentions to wear hearing ing difficulty (Tak and Calvert, 2008). Most U.S. miners are protection (Quick et al., 2008). Also, workers who believe that exposed to noise levels that mandate their enrollment in a hearing protectors are effective at preventing NIHL are more hearing conservation program (HCP) through their employers. likely to use HPDs in noisy situations, while those who do not The U.S. Mine Safety and Health Administration’s (MSHA) believe that HPDs are effective do not use them consistently. 1999 Health Standards for Occupational Noise Exposure, Other factors that reduce hearing protector use include work- codified in 30 CFR 62 (commonly called the “Noise Rule”), ers’ perceptions that they already have poor hearing, that the requires this step for most miners. The mandatory HCP includes devices are uncomfortable and that HPDs can interfere with exposure monitoring, annual audiometry, access to hearing communications, job performance and the ability to hear warn- protectors, training and recordkeeping. NIOSH recommends ing signals (Morata, 2002). Additional barriers, such as lack of additional components beyond those mandated to provide motivation, lack of hearing protector fitting skills and lack of procedural audits, worker motivation, program evaluation and knowledge, can undermine even the most employee-centered integration of engineering and administrative controls as part hearing loss prevention programs. NIOSH has developed sev- of the program. These programs that go beyond the standard eral hearing loss intervention tools targeting specific barriers hearing conservation program requirements are referred to as to effective hearing loss prevention which can be implemented hearing loss prevention programs (HLPP) to reflect the more into a comprehensive hearing loss prevention program. comprehensive and proactive approach (NIOSH, 1996). To enable mines to implement an effective HCP or HLPP the Motivation NIOSH mining hearing loss research program has developed Workers may not take action to protect their hearing because a variety of tools and resources. In particular, several tools they lack the motivation to do so. Without understanding the have been developed to address the need for worker educa- consequences of noise exposure on hearing, a worker may

Figure 1 — NIOSH Hearing Loss Simulator main screen. have little reason to take any action for protection against noise exposure. The NIOSH Hearing Loss Simulator was developed to motivate miners to protect their ears from noise-induced hearing loss. It is a software training and communication tool that allows for self-experience of the impact of NIHL. Self- experiences of symptoms have been found to be positively Figure 2 — NIOSH Roll-Pull-Hold method for insertion of associated with anti-noise attitudes and behaviors (Widen et foam earplugs. al., 2009). The purpose of this tool is to motivate workers to protect their own hearing by allowing them to experience the potential hearing loss they may incur with conditions very how much additional NIHL is experienced by individuals in similar to their “real life” work environment. The main screen the most susceptible quartiles versus those at the population of the Hearing Loss Simulator is shown in Fig. 1. median. Although no individual user can predict their own A user of the Hearing Loss Simulator can adjust various susceptibility, the program can show the range of possible parameters to estimate the hearing loss one would experience expected NIHL. By doing so, the Simulator provides realistic given a specific level of noise exposure over a specific number examples of the negative impact of repeated or prolonged noise of years. The effects are shown visually on a frequency band exposure with data from a large subject pool. control panel while the user listens to audio playback. Addi- The NIOSH Hearing Loss Simulator functions on systems tionally, frequency band sliders are available that allow users with Windows 98 or higher and standard Windows sound sup- to manually input hearing thresholds, from an audiogram, for port and speakers. Projectors and/or headphones may be used example, so that a specific hearing loss can be demonstrated. for certain training applications. The NIOSH Hearing Loss Because hearing in background noise is a more difficult task Simulator and the Hearing Loss Simulator Instruction and than hearing in quiet, the Hearing Loss Simulator also offers Training guide are available for download from the internet a variety of background noise conditions for demonstration. at: www.cdc.gov/niosh/mining/products/product47.htm. Ad- Users can select from several recorded mining worksite sounds ditionally, these tools can be ordered by calling 1–800–CDC– (continuous mining machine, bulldozers, processing machines), INFO (1–800–232–4636). as well as standard generic background noises, such as multi- talker babble. Customized sounds may be recorded using a Hearing protector fitting skills high-quality microphone for further individualization of work- Lack of hearing protector fit skills is another barrier that place noise conditions. Through manipulation of these various impedes workers’ attempts to prevent noise-induced hearing conditions, a user can experience a range of estimated hearing loss. Hearing protection devices (HPDs) marketed in the U.S. impairments in a variety of background noise conditions. This are tested in laboratories to determine their Noise Reduction variety allows for demonstration of noise conditions that are Rating (NRR). This rating is intended to represent the amount very similar to a user’s own noise exposures and, therefore, an of noise protection that the protector can provide. However, increased understanding of how their own working conditions the attenuation values obtained at work sites are often much may negatively impact their hearing ability. less than those achieved in the laboratory (Berger et al., 1996). The Simulator gains realism by basing its approximation With incorrect HPD fit, as often occurs with untrained users, of the NIHL experience on models derived from hearing im- little or no protection from noise may be obtained. NIOSH paired populations. The software performs calculations based has developed two tools to aid users of HPDs in achieving on the ANSI standard S3.44, Determination of Occupational adequate fit. The Roll-Pull-Hold method and QuickFit earplug Noise Exposure and Estimation of Noise-Induced Hearing fit tester are NIOSH products aimed to alleviate two specific Impairment (ANSI, 2006). This standard provides algorithms issues with fitting earplugs. for predicting hearing loss based on age and noise exposure. These algorithms were derived from studies of large popula- Roll-Pull-Hold. It can be difficult to understand and re- tions, including some groups with no exposure to hazardous member the instructional wording and small print that is often noise and other groups that experienced various levels and found on the packaging of soft foam earplugs. Additionally, durations of noise exposure. The Simulator can demonstrate the directions for earplug insertion can be inconsistent between the individual variability in susceptibility to NIHL by using manufacturers or the packaging may be discarded before the its population quartile adjustment. For instance, it can show directions are read and comprehended. NIOSH has developed

Figure 4 — Front pages of English and Spanish versions Figure 3 — Worker adjusting the volume control on the of “Inquiring Ears Want to Know” fact sheet. QuickFit device to set his hearing threshold prior to insert- ing an earplug. and published the Roll-Pull-Hold method to simplify the inser- was used to process a sample of random noise, limiting the tion of soft foam earplugs by standardizing the instructions to band to the region between 500 and 2,000 Hz. This specific test focus on three words essential to the insertion task. By breaking signal was chosen for three reasons. It is part of the standard the instructions into three simple steps, each linked to a single set of frequencies used in fit testing procedures, as well as word, users of foam earplugs are able to remember the insertion audiometric testing; it is the most audible of those signals to procedure without referring the packaging, and in turn achieve the most people, because it is not typically masked by lower a better plug fit. The most critical departure from standard frequency sounds or impacted by noise-induced or age-related instructions is the use of the term “pull” to remind users that hearing loss and it is not affected by A-weighting. The test they need to pull the pinna of the ear outward and upward to signal was then processed to pulse at one-second intervals. facilitate insertion. Prior to this, most earplug instructions used The QuickFit also streamlines testing by checking for just one the word “insert” or other non-specific terms to describe this attenuation value: 15 decibels. If a protector is poorly fitted, it crucial step. Figure 2 is a visual representation of the NIOSH will usually provide far less than 15 decibels of attenuation. This Roll-Pull-Hold method. simplified method of fit testing proves more time-effective for An unpublished pilot study of 308 coal miners was conducted use at busy worksites and is simple enough for workers to use to determine the benefits of the Roll-Pull-Hold technique. Sub- without much training. A three-step process is followed that jects who were observed to complete none of the three steps can be completed for both ears in less than five minutes. Figure attained an average of only 15 dB of attenuation at 1,000 Hz. 3 shows a miner using the QuickFit to assure that his earplugs Subjects who completed all three steps attained an average of are properly inserted. The user first holds the QuickFit to their 24 dB of attenuation, a 9 dB improvement. ear and adjusts the output to their hearing threshold (where they can just barely detect the output). The user then inserts an QuickFit. Personal fit testing is an effective and proven way earplug following the NIOSH Roll-Pull-Hold method or other to determine the amount of protection a worker is receiving method suited to the type of earplug being used. After insertion, from their hearing protection; however, fit-test systems can be the user will again hold the QuickFit over the protected ear expensive and impractical to implement at worksites. NIOSH and press the “boost” button, which raises the level of the test has developed the QuickFit as an affordable, simpler fit-testing tone by 15 dB. If the user cannot hear the boosted signal, they device for use in classroom training and at the worksite. have successfully achieved at least 15 dB of hearing protection. The NIOSH QuickFit is a highly simplified variation of However, if the signal is still audible, they have not achieved laboratory fit evaluations such as the procedure specified in enough attenuation from the earplug and should re-insert or ANSI S12.6 (ANSI/ASA, 2008). The simplicity and low cost of try another style of earplug. the device result from its design. The electrical components are QuickFitWeb is an online application that uses the same test derived by using off-the-shelf MP3 player components, with a tone as the handheld device, except that the sounds are played few other parts, housed in the shell of a standard earmuff style through computer speakers. This application, available to those hearing protector. In contrast to most other fit-test systems, only with access to a computer and the internet, allows for testing one critical test frequency is used with the QuickFit, which of earmuff style protectors as well as plugs. The web version saves time and allows for a simple three-step procedure that eliminates the need for the handheld device, but does not allow can be done at the worksite. for testing earplug fit separately for left and right ears. The The QuickFit does not replace more complex systems that QuickFitWeb is available through the NIOSH website: www. provide users with a personal attenuation rating (PAR), by cdc.gov/niosh/mining/topics/hearingloss/quickfitweb.htm. testing hearing protector fit at several frequencies. Instead, the QuickFit tests only one octave band, 1,000 Hz, in a “go” Hearing test knowledge or “no-go” paradigm designed to determine whether a user Audiometric testing is the standard monitoring method has achieved at least 15 dB of attenuation with earplugs. To in hearing conservation programs. Yet, audiograms remain arrive at this 1,000-Hz octave band, a digital bandpass filter misunderstood by most workers, leading to confusion and indifference regarding their hearing status and necessary steps and the QuickFit. For improved comprehension of hearing for hearing protection. NIOSH developed the “Inquiring Ears test results and basic hearing knowledge, the “Inquiring Ears Want to Know” fact sheet to increase worker knowledge about Want to Know” fact sheet provides practical, easily understood their own hearing status. This one-page (front and back) flyer information. Workers can carry the sheet away from the test is designed to augment the verbal information provided to and retain it with their test results for future reference. By workers after an audiometric test, with written information targeting specific behavioral barriers, hearing loss prevention and visual images for a greater retention of the most salient programs are likely to yield greater success in reducing NIHL points. An explanation of test results is provided, along with and improve worker acceptance through understanding of the tips for preventing future hearing loss, a list of non-noise purpose of the program. related causes of hearing loss, as well as a reminder of the Roll-Pull-Hold method for earplug insertion. The document Disclaimer is appropriate for all noise-exposed workers through simple The findings and conclusions in this report are those of the wording and vivid images intended to convey complex mes- author(s) and do not necessarily represent the views of the sages. A Spanish translation is also available to accommodate National Institute for Occupational Safety and Health. Refer- the growing Spanish-speaking segment of the workforce. Figure ence to specific brand names does not imply endorsement by 4 shows the front page of the English and Spanish versions the National Institute for Occupational Safety and Health. of the fact sheet. The purpose of the document is not only to increase worker knowledge about their hearing, but to motivate References ANSI, 2006, Determination of Occupational Noise Exposure and Estimation of proactive behaviors towards hearing loss prevention efforts. Noise-Induced Hearing Impairment, ANSI S3.44-1996 (R 2006), New York: The “Inquiring Ears Want to Know” fact sheet has been American National Standards Institute. field-evaluated with public health professionals as well as ANSI/ASA, 2008, Methods for Measuring the Real-Ear Attenuation of Hearing Protectors, ANSI/ASA S12.6-2008. New York: American National Standards miners to assure the clarity and simplicity of the intended Institute. messages. Suggestions from the public health professionals Berger, E.H., Franks, J.R., and Lindgren, F., 1996, “International review of field regarding content and images were implemented to make the studies of hearing protector attenuation,” in: Axelsoson, A., Borchgrevink, H., Hamernik, R., Hellstrom, P., Henderson, D., Salvi, R.(eds.), Scientific fact sheet as useful yet simple as possible. The document was Basis of Noise-Induced Hearing Loss, New York: Thieme Medical Publishers. also pilot-tested with a group of mining trainees to confirm that Morata, T., 2002, “Issues regarding hearing protection in manufacturing and the text and images were communicated in a way that could be mining,” Proceedings of the 144th Meeting of the Acoustical Society of understood by the target audience. The “Inquiring Ears Want America, Dec. 2-6, 2002, Cancun, Mexico. NIOSH, 1996, Preventing Occupational Hearing Loss, A Practical Guide, DHHS to Know” fact sheet is available online for download at: www. Publication, NIOSH, No. 96-110. cdc.gov/niosh/mining/pubs/pdfs/2008-102.pdf or by calling Quick, B.L., Stephenson, M.T., Witte, K., Vaught, C., Booth-Butterfield, S., and 1–800–CDC–INFO (1–800–232–4636). Patel, D., 2008, “An examination of antecedents to coal miners’ hearing protection behaviors: A test of the theory of planned behavior,” Journal of Safety Research, Vol. 39, pp. 329-338. Conclusion Tak, S. and Calvert, G.M., 2008, “Hearing difficulty attributable to employment The Hearing Loss Simulator, QuickFit, Roll-Pull-Hold by industry and occupations: An analysis of the national Health Interview Survey- United States, 1997-2003,” Journal of Occupational and Environmental method and “Inquiring Ears Want to Know” fact sheet can Medicine, Vol. 50, pp. 46-56. be implemented in hearing loss prevention programs indi- Tak, S., Davis, R.R., and Calvert, G.M., 2009, “Exposure to hazardous workplace vidually or as a suite of interventions. Worker motivation noise and use of hearing protection devices among US workers- NHANES, 1999-2004,” American Journal of Industrial Medicine, Vol. 52, pp. 358-371. can be addressed through specific examples with the Hearing Widen, S.E., Holmes, A.E., Johnson, T., Bohlin, M., and Erlandsson, S.I., 2009, Loss Simulator. Hearing protector fit skills can be improved “Hearing, use of hearing protection, and attitudes towards noise among young through hands-on training using the Roll-Pull-Hold method American adults,” International Journal of Audiology, Vol. 48, pp. 537-45.